This invention relates to electro-optic displacement measuring apparatus and systems and more particularly to new and improved fiber optic displacement measuring apparatus and system having the ability to extend and control the dynamic range of the sensor over that of the prior art and measure changes in gap spacing without relying on absolute intensity measurements.
Various optical measuring systems are taught by U.S. Pat. Nos. 3,327,584; 3,586,400; 3,788,741; 3,940,608; and 4,037,958.
U.S. Pat. No. 3,327,548 by inventor Curtis D. Kissinger teaches the use of optical fibers for conduction of light directed toward and bounced from a reflective surface for distance measurement.
U.S. Pat. No. 3,788,741 by inventor Lester W. Buechler teaches the use of fiber optics to conduct light toward and reflected from an object whose distance from the end of the fiber optic is being measured. The changes in the intensity of the returning light due to focus changes with object movement is detected and related to distance.
U.S. Pat. No. 3,856,400 by inventor Horst Hartman and U.S. Pat. No. 4,037,958 by inventor Horst Schmidt teach the use of a grating in distance measuring optical instruments.
U.S. Pat. No. 3,940,608 by inventor Curtis D. Kissinger teaches fiber optic bundles in a "Y" configuration with one arm of the bifurcated ends of the Y for transmitting a source light and the other bifurcated end receives light from the target displaced from the end of the Y opposite the bifurcated end (second end) an unknown distance which is to be measured. The amount of light returning through the receiver end is related to the distance of the target from the second end of the Y.
None of the prior art references teach dispersing the incident light through a grating creating a spectrum to a reflective surface and detecting the reflected light therefrom at one or several different wavelengths. This feature greatly increases the utility of the fiber optic sensor.
There has not been an optical measuring system which includes a lens and grating added thereto that has an extended dynamic range, responsive control and is not intensity or focus dependent until the emergence of the instant invention.